1. Field of the Invention
The present invention relates to a dental apparatus. More particularly, it relates to the dental apparatus capable of cutting teeth, forming root canals and applying to dental implant, for example, by driving a cutting tool.
2. Description of the Related Arts
Conventionally, a dental apparatus wherein the rotation of its cutting tool (file) is controlled depending on the load torque applied to the cutting tool to prevent the breakage of the cutting tool when expanding a root canal, for example, has been proposed. In this dental apparatus, the cutting tool rotates reversibly or stops when the load torque reaches a reference torque or more (for example, Japanese Non-examined Patent Publication No. Hei 9-38108).
If a root canal is bent for example, however, the load increases spontaneously even when the operator has no intention of increasing the load, and the rotation of the cutting tool stops or reverses unexpectedly. Hence, the operator is required to carry out cutting while being fully careful so that the load torque does not reach a reference load torque. However, the smaller the load, the lower the efficiency of the cutting. On the other hand, if the load is increased so as to be nearly equal to the reference load torque, the cutting tool stops or reverses frequently, thereby lowering the efficiency of the cutting in some cases. In other words, it was impossible to carry out the cutting at an appropriate load not exceeding the reference load efficiently without worries.
Furthermore, the operator is required to carry out the cutting while simultaneously checking the measurement result of a root canal length and the torque. In the conventional dental apparatus, these values were not displayed so as to be checked simultaneously, whereby the efficiency of the cutting was low.